Slip ring and brush holder construction for electrodynamic machinery



' Feb. 3, 1959 FOR ELECTRODYNAMIC MACHINERY Filed June 26, 1956INVENTOR.

ATTORNEY SLIP RING AND BRUSH HOLDER CONSTRUCTIQN FOR ELECTRODYNAMICMACHINERY William E. Brill, Indianapolis, Ind, assignor to GeneralMotors Corporation, Detroit, Micln, a corporation of DelawareApplication June 26, 1956, Serial No. 593,888 6 Claims. (Cl. 310-239)This invention relates to an electrodynamic machine and moreparticularly to a slip and brush holder construction for anelectrodynamic machine of the type having a rotatable electromagneticarmature member including a magnetic field inducing coil or winding.

In conventional slip ring and brush carrier constructions forelectrodynamic machines of the type described, the slip rings aremounted on the rotatable armature member and the brush carriers arereciprocably or pivotally mounted on a stationary supporting member suchas a housing. With such constructions there is no assurance that thebrush carriers will be mounted or maintained in concentric relation tothe slip rings. This is particularly true in those applications Wherethe slip ring mounting portion of the armature assembly is substantiallyoverhung from the journal bearings of the armature assembly or where thearmature assembly is susceptible to dynamic unbalance at certain speeds.This lack of concentricity results in harmonic reciprocation andvibratory movement of the brushes out of contact with the slip ringswith resultant arcing therebetween unless brush biasing springs ofsufiicient rate are utilized. However, the use of such springs resultsin relatively higher bearing pressures and thus increases the frictionaldrag and wear between the slip rings and brushes.

Among the principal objects of the invention are to provide an improvedslip ring and brush holder assembly adapted to insure the concentricityof the several brushes relative to the slip rings; to provide such anassembly which is of a simplified and economical design and adapted foruse on existing electrodynamic machinery of the type described; and toprovide such an assembly of a construction minimizing the biasing forcesneces sarily applied to the brushes to maintain them in properelectrical contact with the slip rings.

The foregoing and other objects, advantages and features of theinvention will be more clearly understood from the following descriptionhaving reference to the accompanying drawing showing a sectional View ofa portion of a magnetic particle coupling embodying a preferredembodiment of the invention.

In the illustrative embodiment of the invention, a magnetic particlecoupling 1 is shown comprising an armature assembly 10 including twoannular members 12, 12 of magnetic material which are secured to theopposite end faces 14, 14 of an outer portion 16 of an intermediate orcentral member 18 of magnetic material. The intermediate member 18 has aweb portion 20 which extends radially inwardly from the outer poleportion and is mounted on a hub 22 secured to a rotatable shaft 24. Theadjacent faces of the pole pieces are recessed to mount two annularfield coil windings 26 and 28 therebetween and to axially separate theperipheral portions of the pole members 12, 12 and 18 to establishannular magnetic poles.

The armature assembly 10 is spacedly embraced by an inductor drumassembly 30 comprising a cylindrical member 32 and two end plates 34 and26 secured to the opposite ends of the cylindrical member 32. The member32 and preferably the end plates 34 and 36 are made of magneticmaterial. The end plates 34 and 36 extend radially inwardly from thecylindrical member and terminate in portions 38 and 40, respectively,which coact with elements of two magnetic seals 42 and 44 and thearmature hub 22 to effectively seal a quantity of magnetic particlesindicated at 46 within the coupling. The end plate 36 serves as a loadcarrying member and is secured adjacent its central portion 40 to asecond rotatable shaft 48 which is journaled with respect to the shaftby a bearing 50. The shaft 48 is also journaled in a suitable supportingstructure, a portion of which is shown at 5 by a bearing 56.

The windings 26 and 28 are oppositely wound and are electricallyenergizable to establish two substantially toroidal magnetic fieldsbridging the annular spaces between the cylindrical member 32 and theperipheral surfaces of the pole members 12, 12 and 18 of the inductordrum and armature assemblies, and effecting a load transmitting bondtherebetween through the magnetic particles. This bonding action isproportional to the magnetic fields effected by the electricalenergization of the field coils 26 and 23 up to a point at which currentpassing through the coils is sutlicient to efiectively lock the inductordrum and armature assemblies together by the magnetic bonding action ofthe magnetic particles. Since the two windings are oppositely wound,these magnetic fields establish the annular pole members 12, 12 asmagnetic po es of the same polarity and the intermediate pole member 18as a magnetic pole of the opposite polarity.

The field coil windings are connected to a controllable source ofelectrical potential, not shown, through suitable leads and a slip ringand brush carrier assembly 60 constructed in accordance with theinvention. The ring and brush carrier assembly 60 includes a turks-headshaped ring carrier 62 having an inner cylindrical portion 64 and anouter cylindrical portion 66 joined by a radially-extending base portion68 which is secured to the end of the shaft 24. The outer cylindricalportion of the ring carrier 62 mounts three axially-spaced slip rings 7%72 and 74 insulated therefrom by an insulator pad 76 and connected tothe field coils 26 and 28 by suitable leads 78, 80, @2, respectively,mounted in an insulating sheath 84 running axially through the rings.

The inner cylindrical portion 64 of the ring carrier mounts twoanti-friction bearings 88, 88 which, in turn, rotatably mounts aturks-head shaped brush carrier 90 which telescopically embraces theouter cylindrical portion 66 of the member 62 and the slip rings '70, 72and 74. The bearings 88 are retained between the portion 64 and an innercylindrical portion 92 of the brush carrier 90 by a spanner nut 94 and aretaining collar 96 and are axially separated by spacer sleeve 93. Anouter cylindrical portion 160 of the brush carrier 90 reciprocablymounts three brushes 102, 1' 4 and 106, which are biased into bearingcontact with the outer surface of the slip rings 70, "/2 and 74,respectively, by semi-elliptical leaf springs 108 interposed between acover plate 110 carried by the brush carrier 20 and insulating caps 112carrying the individual brushes. The brushes 102, 104 and 106 areconnected to the source of electrical potential by leads 114, 116 and116, respectively.

The brush carrier 90 is retained against rotation by a tie rod 120 whichis universally connected thereto by a resilient ball-and-socketconnection 122 and is universally connected at its opposite end to astationary structure, not shown, by a similar swivel connection, alsonot shown. The resilient ball-and-socket connections 122 intermediatethe carrier 90, the tie rod 120, and the stationary structure furtherserve to damp rotative and radial vibratory movement of the carrierunder dynamic conditions.

From the foregoing description it will be seen that the several objectsof the invention are obtained in the illustr'ative embodiment; the ringand brush carriers being of a compact and simplified design maintainingthe brushes in concentric relation with the slip rings under alloperative conditions, thus reducing the slip ring and brush arcing andfrictional wear which are inherent in conventional slip ring and brushmounting constructions where the brushes are carried by the supportingstructure.

While only one specific structural embodim nt of invention has beenshown and described for purposes of illustration, it will be appreciatedthat various minor modifications may be made without departing fro n thespirit and scope of the invention, as defined in the following claims.

I claim:

1. A slip ring and brush carrier construction for an electrodynamicmachine having a rotatable magnetic armature including a magnetic fieldinducing coil, said construction comprising, in combination, a shaftmounting said armature member, a first turks-head shaped member havingan inner cylindrical portion and an outer cylindrical portion joined bya radially-extending base portion, said base portion being secured tothe end of the shaft, at least one slip ring mounted on said outer cylindrical portion and insulated therefrom, said slip ring electricallyconnected to said field coil, a second turl shead shaped member havingan inner cylindrical portion rotatably mounted by said inner cylindricalportion of said first turks-head shaped member, said second turkeheadshaped member having an outer cylindrical portion concentricallyembracing the outer cylindrical portion of said first turks-head shapedmember and said slip ring, said outer cylindrical portion of said secondturks-head shaped member reciprocably mounting at least one contactbrush for each of said slip rings, spring means carried by said secondLurks-head shaped member and biasing said contact brushes into bearingcontact with the outer surface of said slip rings and a tie roduniversally interconnecting said second turkshead shaped member to astationary supporting structure.

2. A slip ring and brush carrier construction as set forth in claim 1and including resilient means associated with said tie rod and adaptedto damp vibratory movement of said second turks-head shaped member.

3. In a machine having a shaft mounted therein for rotation about anaxis and having an electrically ener gizable device mounted on saidshaft for rotation therewith, an electrical contact assembly comprisinga first cylindrical member mounted on said shaft and rotatabletherewith, at least one annular current collector mountedcircumferential-1y on said first cylindrical member, said currentcollectors being insulated from each other and electrically connected tosaid device, a second cylindrical member rotatably mounted with respectto said first cylindrical member and having a cylindrical portionextending longitudinally of and in radially spaced concentric relationtherewith, at least one contact brush for each of said annular currentcollectors mounted for independent movement with respect to saidcylindrical portion, spring means carried by said second member forindividually biasing each of said contact brushes to maintain electricalcontact with the outer surface of said annular current collectors, andmeans Ior connecting said second member to the supporting structure toretain said second member against rotation with said cylindrical member,said last-mentioned means including means for resiliently dampingrotational vibratory movement of said second member.

4. In a machine having a shaft mounted therein for rotation about anaxis and having an electrically energizable device mounted on said shaftfor rotation therewith, an electrical contact assembly comprising acylin drical member mounted on said shaft and rotatable therewith, anannular current collector mounted circumferentially on said cylindricalmember and electrically connected to said device, a second membersupported by and rotatable with respect to said cylindrical member, saidsecond member having a portion thereof extending longitudinally of andin radially spaced concentric relation with said cylindrical member,said portion mounting a contact brush engageable with said annularcurrent colmeans carried by said second member for resil- 1g saidcontact brush to maintain electrical contact With the outer surface ofsaid annular current collector, and means for retaining said secondmember against'rotation with said cylindrical member, saidlastinentioned means including means for resiliently damprotationalvibratory movement of said second mem- 5. An electrical contactconstruction for an electrical machine having a rotatably mountedelectrical element, said construction comprising, in combination, saidrotatably mounted electrical element, a first member having an innercylindrical portion and an outer cylindrical portion joined by aradially extending base portion, said base portion being secured to theelectrical element in coaxial relation thereto, a plurality of contactelements mounted circumferentially of the outer cylindrical portion,said contact elements being in spaced electrically insulated relation toeach other and connected electrically to said electrical element, asecond member having an inner cylin drical portion rotatably mounted bythe inner cylindrical portion of the first member and an outer portionextending longitudinally of the outer cylindrical portion of the firstmember and of the contact elements mounted thereon and in radiallyspaced relation thereto, at least one contact brush r'eciprocablymounted by the outer portion of the second member for engagement withthe contact elements, spring means interposed between the second memberand each of said brushes for independently biasing said contact brushesinto electrical contact with the contact elements, and a tie roduniversally interconnecting the second member to a stationary portion ofthe machine. v

6. An electrical contact construction for a rotatably mounted electricalelement comprising a first member having two radially spaced cylindricalportions joined by'an intermediate radially extending portion, saidfirst member being carried by said electrical element in coaxialrelation thereto, a plurality of contact elements mountedcircumferentially of one of said cylindrical portions in electricallyinsulated relation to each other and connected electrically to saidelectrical element, a second member rotatably mounted by the other ofthe cylindrical portions of the first member and having a portionthereof extending longitudinally of said one cylindrical portion or" thefirst member in radially spaced relation to the contact elements mountedthereon, at least one contact brush mounted by said portion of thesecond member for movement into engagement with the contact elements,spring means interposed between the second member and each of saidbrushes for independently biasing said contact brushes into electricalcontact with the contact elements, and means for universally connectingthe second member to a stationary portion of the machine.

References Cited in the file of this patent

